The present invention relates to combustion chamber valve gear for an internal combustion engine. In particular, the invention relates to engine valve gear of the type having an overhead rocker arm pivoted about a fulcrum disposed intermediate the end of the rocker arm. More particularly, the invention relates to engine valve gear having rocker arms pivoted intermediate the ends about a fulcrum mounted on a post anchored to the engine. Such a post mounted rocker amrs for engine valve gear are usually formed in a generally cupped shaped configuration with the fulcrum member received over the post and having pivot surfaces formed thereof which slidably engage corresponding pivot surfaces formed on the rocker arm in the region surrounding the aperture, wherein the rocker arm is received over the post.
Engine valve gear having rocker arms pivoted about a fulcrum of the above described type have found widespread usage in automotive engines of the type having push-rod actuated valve gear; and, in particular, in automotive engines having a v-type configuration. However, in valve gear having rocker arms pivoted about a post mounted fulcrum, it has been found that a substantial amount of friction is generated in the sliding of the rocker arm about the fulcrum, and this type of pivot requires constant lubrication in addition to consuming engine power in the friction forces.
It has, therefore, been desired to find a way of providing a fulcrum for the pivotal motion of an engine valve gear rocker arm mounted over a post in a manner which would reduce the frictional forces generated in the pivot. It has been proposed to provide roller bearings in the fulcrum or pivot of an engine valve gear rocker arm to reduce friction. However, in order to employ roller bearings in engine valve gear rocker arms of the type mounted for over a post for pivotal motion, it has been necessary to completely redesign the rocker arm and the fulcrum members attached to the post. Thus, it has long been desired to find a way or means of providing an easily adaptable roller bearing pivot or fulcrum for a post mounted engine valve gear rocker arm. It has particularly been desired to provide a way or means of retrofitting a roller bearing equipped pivot or fulcrum into existing cup-shaped engine valve gear rocker arm without requiring alteration of the existing rocker arms or reworking of the mounting post location or attachment to the engine.